Measurements of Microwave Power Absorbed during ECR Plasma Heating at the L-2M Stellarator

Plasma Physics Reports - The results are presented from measurements of the power absorbed in plasma of the L-2M stellarator in experiments on the electron cyclotron resonance (ECR) plasma heating...     

Non-Radiative Dissipation of Absorbed Excitation Energy Within Photosynthetic Apparatus of Higher Plants

The review deals with thermal dissipation of absorbed excitation energy within pigment-protein complexes of thylakoid membranes in higher plants. We focus on the de-excitation regulatory processes within photosystem 2 (PS2) that can be monitored as non-photochemical quenching of chlorophyll (Chl) a fluorescence consisting of three components known as energy-dependent quenching (q_E), state-transition quenching (q_T), and photoinhibitory quenching (q_I). We summarize the role of thylakoid lumen pH, xanthophylls, and PS2 proteins in q_E mechanism. Further, both the similarity between q_E and q_I and specific features of q_I are described. The other routes of thermal energy dissipation are also mentioned, that is dissipation within photosystem 1 and dissipation through the triplet Chl pathway. The significance of the individual de-excitation processes in protection against photo-oxidative damage to the photosynthetic apparatus under excess photon supply is stretched.     

微波提取香水莲花总黄酮的工艺研究

该文研究了微波法提取香水莲花总黄酮的工艺。采用比色法测定黄酮的含量。利用单因素实验和正交实验考察了乙醇浓度、微波功率、微波时间、料液比对黄酮得率的影响,确定了最佳工艺为:用70%的乙醇溶液,微波功率250W,提取时间40 min,液料比25∶1,提取的总黄酮得率最高。     

平板式光生物反应器培养液混合强度对螺旋藻生长的影响

目的：探讨平板式光生物反应器内培养液混合对螺旋藻生长的影响规律。方法：在平板式光生物反应器中进行钝顶螺旋藻（Spirulina platensis）户内和户外培养,通过改变通入反应器内气体的流量来控制培养液的混合强度,测定藻细胞的面积产量和叶绿素含量。结果：在一定的混合强度范围内,藻细胞的面积产量随着混合强度的增加而增加;室内培养时,混合强度的改变不会影响藻细胞的光合反应特性,户外高密度培养时,培养液混合强度的改变会造成藻细胞光合反应特性的变化。结论：强化培养液的混合可以提高螺旋藻产量。     

A Simple Alternative Approach to Assessing the Fate of Absorbed Light Energy Using Chlorophyll Fluorescence

We propose a simplified alternative method for quantifying the partitioning of excitation energy between photochemistry, fluorescence and thermal dissipation. This alternative technique uses existing well-defined quantum efficiencies such as Phi(PS II), leaving no 'excess' efficiency unaccounted for, effectively separates regulated and constitutive thermal dissipation processes, does not require the use of F(o) and F'(o) measurements and gives very similar results to the method proposed by Kramer et al. [(2004) Photosynth Res 79: 209-218]. We demonstrate the use of the technique using chlorophyll fluorescence measurements in grapevine leaves and observe a high dependence on thermal dissipation processes (up to 75%) at both high light and low temperature.     

Influence of Plasma Unsteadiness on the Spectrum and Shape of Microwave Pulses in a Plasma Relativistic Microwave Amplifier

Dependence of the shape of a microwave pulse in a plasma relativistic microwave amplifier (PRMA) on the initial plasma electron density in the system is detected experimentally. Depending on the plasma density, fast disruption of amplification, stable operation of the amplifier during the relativistic electron beam (REB) pulse, and its delayed actuation can take place. A reduction in the output signal frequency relative to the input frequency is observed experimentally. The change in the shape of the microwave signal and the reduction in its frequency are explained by a decrease in the plasma density in the system. The dynamics of the plasma density during the REB pulse is determined qualitatively from the experimental data by using the linear theory of a PRMA with a thin-wall hollow electron beam. The processes in a PRMA are analyzed by means of the KARAT particle-in-cell code. It is shown that REB injection is accompanied by an increase in the mean energy of plasma electrons and a significant decrease in their density.     

Variation in Total Energy Expenditure in Humans

The purpose of this paper is to review current data regarding the factors contributing to variability in total energy expenditure (TEE) among humans. Variation arising from within and between individuals and between study groups will be considered. For within- subject variation, issues relating to experimental and theoretical measurement error will be considered in addition to inherent physiological variation. The literature reporting TEE in various study groups is reviewed, highlighting deficiencies in current comparison methods, and a framework by which TEE can be compared between studies and populations is suggested. For between-subject variation, the effects of differences in body composition, obesity, age and gender upon variation in TEE are examined. Finally, data will be reviewed relating to changes in TEE in response to external manipulation (e.g., activity, overfeeding, stress).     

Assessment of Microwave Cooking on the Bioaccessibility of Cadmium from Various Food Matrices Using an In Vitro Digestion Model

Bioaccessibility represents the maximum amount of pollutant ingested with food that is available for intestinal absorption. The measurement of bioaccessibility can achieve a more accurate risk assessment. Thus, in this study, the bioaccessibility of raw/microwave-cooked store-bought food including carrot, potato, white radish, lotus root, sweet corn, long grain rice, soybean, fleshy prawn, eastern oyster, kelp, and common carp were investigated by applying an in vitro digestion method. A validated microwave digestion/ICP-MS method was applied for determining the concentration of Cd. In this study, the concentration of Cd ranged 3.7–215.8 μg/kg fw in which carrot contained the lowest Cd while the fleshy prawn contained the highest Cd. There are no statistical differences of Cd content in microwave-cooked food and raw food except potato, lotus root, and eastern oyster. Cd in most of the cooked food materials was less bioaccessible than in raw food except sweet corn, potato, and kelp. The bioaccessibility of Cd was around 100 % in either raw or cooked potatoes. Microwave cooking caused the decreasing of bioaccessibility around 0–68 %, depending on different food matrix. Maximal decreasing of Cd bioaccessibility occurred in common carp. Thus, microwave cooking could be a feasible strategy for decreasing Cd bioaccessibility. In addition, the Cd dissolution in oral, gastric, and small intestine phase was different in different food matrix. For most of the investigated food items, Cd was largely migrated either into the oral phase (carrot, potato, white radish, lotus root, raw soybean, kelp, and common carp) or into the gastric phase (sweet corn, cooked soybean, rice, fleshy prawn, and eastern oyster). Our findings will have significant implications for food processing aiming to decrease the absorption of Cd and risk assessment analysis improvements. Further study is needed to use the animal model to validate these results.     

微波提取苦荞麦麸皮总黄酮工艺研究

本文对苦荞麦麸皮总黄酮微波提取工艺进行了研究。试验结果表明:微波提取的最佳工艺条件为微波功率中档,微波加热120 s,乙醇浓度80%,料液比1:50,该工艺条件下总黄酮得率达5.51%;与传统提取方法相比,微波提取法具有节省时间、节约能量、提取效率高、控制方便等优点。     

The Influence of Mixing Frequency and Depth on Phytoplankton Mobility

The influence of mixing frequency and depth on phytoplankton functional group composition (mobile versus immobile species) was studied by enclosure experiments in a shallow, stratified lake. Mixing events were artificially induced at intervals from 2–12 d. The mixing depth was increased from the natural level (4 m) to 6 and 9 m. The mobile phytoplankton in the experiments consisted of cyanobacteria and flagellates. Among the latter, large and rapid swimming species were represented by dinoflagellates. An increase of the relative abundance of gas vacuolated cyanobacteria occurred with increasing frequency of mixing. Additionally Reynolds' hypothesis predicting the occurrence of certain mobile phytoplankton genera in response to the mixing regime could be confirmed for the condition when mixing depth exceeds the euphoric depth.     

A Test of the Dopamine Hypothesis of Microwave Energy Effects

Exposure to low intensity microwave energy has been found to alter the behavior of test animals. Frey and Spector hypothesized that the dopamine systems of the brain may be involved in the mediation of these and other effects of the energy. The dopamine system has been implicated in the regulation of tail pressure behaviors. Thus, microwave energy exposure should modify tail pressure behaviors. This prediction was tested and it was found that microwave energy exposure does affect this set of behaviors. The pressure used as well as odor cues influences the effect.     

The Total Branch Length of Sample Genealogies in Populations of Variable Size

We consider neutral evolution of a large population subject to changes in its population size. For a population with a time-variable carrying capacity we study the distribution of the total branch lengths of its sample genealogies. Within the coalescent approximation we have obtained a general expression—Equation 20—for the moments of this distribution with a given arbitrary dependence of the population size on time. We investigate how the frequency of population-size variations alters the total branch length.MODELS for gene genealogies of biological populations often assume a constant, time-independent population size N. This is the case for the Wright–Fisher model (Fisher 1930; Wright 1931), for the Moran model (Moran 1958), and for their representation in terms of the coalescent (Kingman 1982). In real biological populations, by contrast, the population size changes over time. Such fluctuations may be due to catastrophic events (bottlenecks) and subsequent population expansions or just reflect the randomness in the factors determining the population dynamics. Many authors have argued that genetic variation in a population subject to size fluctuations may nevertheless be described by the Wright–Fisher model, if one replaces the constant population size in this model by an effective population size of the form(1)where N_l stands for the population size in generation l. The harmonic average in Equation 1 is argued to capture the significant effect of catastrophic events on patterns of genetic variation in a population: if, for example, a population went through a recent bottleneck, a large fraction of individuals in a given sample would originate from few parents. This in turn would lead to significantly reduced genetic variation, parameterized by a small value of N_eff. (See, e.g., Ewens 1982 for a review of different measures of the effective population size and Sjödin et al. 2005 and Wakeley and Sargsyan 2009 for recent developments of this concept.)The concept of an effective population size has been frequently used in the literature, implicitly assuming that the distribution of neutral mutations in a large population of fluctuating size is identical to the distribution in a Wright–Fisher model with the corresponding constant effective population size given by Equation 1. However, recently it was shown that this is true only under certain circumstances (Kaj and Krone 2003; Nordborg and Krone 2003; Jagers and Sagitov 2004). It is argued by Sjödin et al. (2005) that the concept of an effective population size is appropriate when the timescale of fluctuations of N_l is either much smaller or much larger than the typical time between coalescent events in the sample genealogy. In these limits it can be proved that the distribution of the sample genealogies is exactly given by that of the coalescent with a constant, effective population size.More importantly, it follows from these results that, in populations with variable size, the coalescent with a constant effective population size is not always a valid approximation for the sample genealogies. Deviations between the predictions of the standard coalescent model and empirical data are frequently observed, and there are a number of different statistical tests quantifying the corresponding discrepancies (see, for example, Tajima 1989, Fu and Li 1993, and Zeng et al. 2006). The analysis of such deviations is of crucial importance in understanding, for example, human genetic history (Garrigan and Hammer 2006). But while there is a substantial amount of work numerically quantifying deviations, often in terms of a single number, little is known about their qualitative origins and their effect upon summary statistics in the population in question.The question is thus to understand the effect of population-size fluctuations on the patterns of genetic variation, in particular for the case where the scale of the population-size fluctuations is comparable to the time between coalescent events in the ancestral tree. As is well known, many empirical measures of genetic variation can be computed from the total branch length of the sample genealogy (the expected number of single-nucleotide polymorphisms, for example, is proportional to the average total branch length).The aim of this article is to analyze the distribution of the scaled total branch length T_n for a sample genealogy in a population of fluctuating size, as illustrated in Figure 1. For the genealogy of n ≥ 2 lineages sampled at the present time, the expression ⌊NT_n⌋ gives the total branch length in terms of generations. Here ⌊Nt⌋ is the largest integer ≤Nt, and the scaling factor N is a suitable measure of the number of genes in the population and serves as a counterpart of the constant generation size of the standard Wright–Fisher model.Open in a separate windowFigure 1.—The effect of population-size oscillations on the genealogy of a sample of size n = 17 (schematic). Left, genealogy described by Kingman''s coalescent for a large population of constant size, illustrated by the light blue rectangle; right, sinusoidally varying population size. Coalescence is accelerated in regions of small population sizes and vice versa. This significantly alters the tree and gives rise to changes in the distribution of the number of mutations and of the population homozygosity.A motivating example is given in Figure 2, which shows numerically computed distributions ρ(T_n) of the total branch lengths T_n for a particular population model with a time-dependent carrying capacity. The model is described briefly in the Figure 2 legend and in detail in a model for a population with time-dependent carrying capacity. As Figure 2 shows, the distributions depend in a complex manner on the form of the size changes. We observe that when the frequency of the population-size fluctuations is very small (Figure 2a), the distribution is well described by the standard coalescent result(2)(Hein et al. 2005). When the frequency is very large (Figure 2e), Equation 2 also applies, but with a different time scaling reflecting an effective population size: t on the right-hand side (rhs) in Equation 2 is replaced by t/c with c = N/N_eff. Apart from these special limits, however, the form of the distributions appears to depend in a complicated manner upon the frequency of the population-size variation. The observed behavior is caused by the fact that coalescence proceeds faster for smaller population sizes and more slowly for larger population sizes, as illustrated in Figure 1. But the question is how to quantitatively account for the changes shown in Figure 2.Open in a separate windowFigure 2.—Numerically computed distributions of the scaled total branch lengths T_n in genealogies of samples of size n = 10. The model employed in the simulations is outlined in a model for a population with time-dependent carrying capacity. It describes a population subject to a time-varying carrying capacity, K_l = K₀(1 + ɛ sin(2πνl)). The frequency of the time changes is determined by ν, and l = 1, 2, 3, … labels discrete generations forward in time. The parameter N = K₀ describes the typical population size, which is taken here to be equal to the time-averaged carrying capacity. a–e show for populations with increasingly rapidly oscillating carrying capacity. The dashed red line in a shows that in the limit of low frequencies the standard coalescent result, Equation 2, is obtained. The dashed red line in e shows that also in the limit of large frequencies the standard coalescent result is obtained, but now with an effective population size. The dashed red line in d is a two-parameter distribution, Equation 41, derived in comparison between numerical simulations and coalescent predictions. Further numerical and analytical results on the frequency dependence of the moments of these distributions are shown in Figure 4. Parameter values used: K₀ = 10,000, ɛ = 0.9, and r = 1 (see a model for a population with time-dependent carrying capacity for the exact meaning of the intrinsic growth rate r) and (a) νN = 0.001, (b) νN = 0.1, (c) νN = 0.316, (d) νN = 1, and (e) νN = 100.We show in this article that the results of the simulations displayed in Figure 2 are explained by a general expression—Equation 20—for the moments of the distributions shown in Figure 2. Our general result is obtained within the coalescent approximation valid in the limit of large population size. But we find that in most cases, the coalescent approximation works very well down to small population sizes (a few hundred individuals). Our result enables us to understand and quantitatively describe how the distributions shown in Figure 2 depend upon the frequency of the population-size oscillations. It makes possible to determine, for example, how the variance, skewness, and the kurtosis of these distributions depend upon the frequency of demographic fluctuations. This in turn allows us to compute the population homozygosity and to characterize genetic variation in populations with size fluctuations.The remainder of this article is organized as follows. The next section summarizes our analytical results for the moments of the total branch length. Following that, we describe the model employed in the computer simulations. Then, corresponding numerical results are compared to the analytical predictions. And finally, we summarize how population-size fluctuations influence the distribution of total branch lengths and conclude with an outlook.     

The Influence of Ionizing Radiation on Itraconazole in the Solid State

The aim of this study was to investigate the ionizing radiation effects, in the form of an electron beam, on itraconazole (ITR) in the solid phase. It was found that the ITR, under the influence of a standard 25 kGy dose of radiation used for the sterilization of drug substances, decomposed at 0.4%. Moreover, a gentle change of colour and a decrease in melting point does not exceed pharmacopoeial standards causing that ITR can be sterilized by radiation method. The use of high 400 kGy radiation doses resulted in a 6.5% decomposition of the ITR and eight radiodegradation products were found. However, with the exception of differential scanning calorimetry (DSC), the X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR) and ultraviolet-visible (UV-vis) methods showed no changes in the form and the morphology of the crystals. The structures of all those compounds were investigated. It was confirmed that the ITR decomposition takes place by dehalogenation (one of Cl atom elimination), the oxidation in isobutyl residue (beside the triazole ring) and C-O bond rupture.KEY WORDS: antifungal azole, DSC, itraconazole, product radiolysis, radiation sterilization     

A Mechanism For the Influence of Microwave Radiation on Serotonergic Receptors in the Brain

Biophysics - Abstract—The mechanism of the resonance effect of microwave radiation on the brain of laboratory animals was revealed. It was established that microwave radiation releases...     

微波辅助提取荷叶总生物碱的工艺研究

本文通过采用单因素试验和正交试验考察不同因素对荷叶总生物碱提取量的影响,从而探讨微波辅助提取荷叶中总生物碱的最佳工艺.结果表明:微波辅助提取荷叶总生物碱的最佳条件为:pH 2.5 HCI、微波765W辐照2.5 min、固液比1:40、浸提3 h,荷叶总生物碱提取量为175.95μg/g,与热回流提取6 h、索氏提取10.5h的结果接近.因此微波辅助提取技术应用于荷叶总生物碱的提取,具有省时、高效、节能等优点.     

Influx流式仪分选肺腺癌A549细胞SP亚群的条件优化

目的：通过分选肺腺癌A549细胞的侧群细胞（side population cells,SP）,了解影响Influx分选SP的各种因素,为成功分选其他肿瘤细胞的SP亚群提供方法参考.方法：（1）细胞的制备：取对数生长期的细胞,制备单细胞悬液,用Hoechst33342及PI标记染色,同时设计维拉帕米对照组;（2）最佳分选喷嘴的确定：根据对数生长期的A549细胞处于不同的分裂时象的细胞大小,预实验确定最佳分选喷嘴;（3）光信号的调试：用RainbowBeads优化670/30[355]、460/50[355]荧光信号和FSC散射光信号,使光信号最强且变异系数（coefficient ofvariation,CV）最小.（4）最佳液滴延迟的确定：调节振荡频率（frequency）找出最佳液流断点位置,调节振幅（ampitude）优化侧液流信号直到两侧液流信号最稳定,Delay Calculator自动计算液滴延迟,根据Accudrop Beads的分选效果确定最佳液滴延迟;（5）其他指标的调整：调节液滴的充电电压（drop charge）和分选装置的X、Y轴坐标,使测试分选液滴准确达到分选装置中;设置分选参数,分选目的细胞群.结果：同一批次处理的A549肺腺癌细胞,100 μm的喷嘴为分选A549肺腺癌SP亚群的最佳喷嘴;CV值校正后SP比例为19.7％,提高了6％;液滴延迟校正后,其分选效率（efficiency）提高了15％,分选纯度（purity）提高了23％;10 μg/mL的Hoechst3342染色,其SP比例是5μg/mL染色的5倍以上;细胞浓度越稀,分选效率和分选纯度相应提高;活细胞比例越高,SP比例越高.结论：合适的喷嘴大小,是保证高分选效率和高分选纯度的基础;仪器较小的CV值和较精确的液滴延迟、合理的Hoechst33342染料浓度、较高的细胞存活率和适中的细胞浓度是保证高分选效率和高分选纯度的的关键;通过平衡上述影响分选的因素才可能得到最佳的分选效果.     

应用非伤害性取样提取番鸭毛囊组织总RNA

目的:寻求一种从番鸭毛囊组织中高效提取总RNA的方法。方法:探讨了伤害性取样(剪切皮肤毛囊)、非伤害性取样(直接拔取毛囊)2种不同毛囊取样法对总RNA提取质量的影响,并对常用RNA提取方法TRIzol法中研磨和组织匀浆步骤细节稍加改进,琼脂糖电泳检测总RNA质量。结果:2种毛囊取样方法均能提取出高质量的总RNA,其28S、18S和5S条带清晰可见,无DNA污染。结论:非伤害性取样法可作为番鸭毛囊组织总RNA提取的适用取样方法。